Core oils comprising maleic anhydride adducts and reaction products of vicepoxy esters, caprolactam and polyamines



United States Patent CORE OILS CQMPRISING MALEIC ANHYDRIDE ADDUQTS AND REACTION PRODUCTS 0F VIC- EPOXY ESTERS, CAPROLACTAM AND POLY- AMINES Thomas W. Findley, La Grange, and Robert J. Johnson, Chicago, Ill., assignors to Swift & Company, Chicago, Ill., a corporation of Illinois No Drawing. Filed May 4, 1961, Ser. No. 107,653

11 Claims. (Cl. 26018) This invention relates to foundry cores and molds and to the method for making such cores and molds and more particularly to improved binders and core oils used in the production of cores and molds.

In the casting of metals, molds are prepared of sand or other core materials such as zirconi'a, alumina, fluid coke or the like bonded together by a binder. The sand and binder are shaped in the form desired and the form is then baked to develop strength in the core so that it can withstand handling during casting operations without deforming or breaking. The core should have sufficient mechanical strength to retain its form during the casting operation, but should not be so hard as to be difficult to break away and remove from the finished casting. Thus, the most desirable core material is that which can be baked to a given form in a reasonably short period of time and, also, will not lose its strength under extended heating.

Core oils used as hinders to bind the mineral coreforming material should coat the sand with a thin film and should upon heating bind the sand grains together and provide mechanical strength in the formed core. Core oils of the type known heretofore generally have been produced from drying oils such as linseed oil, peri'lla oil, China-wood oil, tung oil, etc. Such heat-polymerizable oils are hardened by oxidation and polymerization through double bonds in the highly unsaturated oil when the oil is exposed to elevated temperatures.

These drying or semi-drying oils possess several deficiencies limiting their desirability as binders in the production of cores. Because these oils polymerize and develop strength by oxidation and this oxidation takes place slowly, extended exposure of the cores to elevated temperatures in baking ovens is necessary. Furthermore, if the cores are inadvertently left in the oven after the optimum amount of polymerization has taken place, oxiclation continues causing degradation of the binder and loss of strength in the core. Even after optimum amount of baking, however, cores utilizing such binders do not have the desired strength and this is demonstrated by the fact that reinforcing wires are often used in such cores to provide additional mechanical strength.

It is, accordingly, an object of this invention to provide core oil compositions which do not possess the aforementioned deficiencies of core oils known heretofore and which cure more rapidly to give stronger cores less subject to heat degradation than those previously known.

Another object of the invention is the provision of an improved, inexpensive core oil composition which possesses a substantial aflinity for the mineral core material and which can be cured in a very short period of time to produce a core having a substantial amount of mechanical strength.

Still another object of the invention is to provide metal casting cores having a high degree of mechanical strength without the necessity for utilizing reinforcing wires.

Another object of the invention is the provision of an improved method for manufacturing inexpensive, high strength cores which are not subject to deterioration and loss of tensile strength.

Additional objects, if not specifically set forth herein,

3,229,963 Patented Nov. 30, 1965 will be readily apparent to those skilled in the art from the detailed description of the invention which follows.

Generally, the compositions providing the benefits of the invention comprise as the major ingredient an adduct of an ethylenically unsaturated hydrocarbon or derivative thereof and a minor amount of polymers formed from polyepoxides and caprolaetam (2-oxohexamethylene imine). The strength of the polymer and the ease with which the polymer is formed are increased by the presence of a small amount of a polyamine. These compositions appear to possess a marked afiinity for mineral core materials such as sand, fluid coke, alumina, zirconia, etc. and appear to coat the mineral particles with a thin film of the binder composition which, when baked, provides a high degree of tensile strength in the core. The polymer is a highly effective binder and can be used in very small amounts in the core oil composition.

More specifically, the core oils of this invention are made up primarily of adducts of aliphatic unsaturated dicar-boxylic acid anhydrides and ethylenically unsaturated hydrocarbons or derivatives thereof, including ethylenically unsaturated higher fatty acids and esters thereof. Diels-Alder type adducts prepared from ethylenically unsaturated dicarboxylic acid anhydrides such as maleic anhydride and dienes can be used, but in the interest of economy maleinized fatty acids and maleinized oils are preferred herein. Mixed with this adduct is the polymer prepared from the polyepoxide, capro'lactam and polyamine. Although the polymer can be employed without any adduct to produce a highly desirable, high strength binder it is preferred, inasmuch as only a very small amount of the polymer is required to give great strength to the core, to use the prereacted adduct as the major component in core oil.

The adduct is prepared from a lower aliphatic dioarboxylic acid anhydride such as maleic anhydride, chloromaleic anhydride, or citraconic acid anhydride and an unsaturated organic composition. Maleic anhydride is the preferred anhydride. The unsaturated organic composition which is combined with the :anhydride to form the adduct may be any hydrocarbon, fatty acid or fatty acid ester having carbon-to-carbon double bonds, free of benzenoid unsaturation. While such dienes as butadiene and isoprene can be employed to form Diels-Alder type adducts, it is preferred that nonconjugated, unsaturated compositions such as unsaturated higher fatty acids and unsaturated higher fatty acid esters be employed in preparing the adduct. Nonconjugated, unsaturated fatty acids and esters thereof form maleinized fatty acids and maleinized oils with maleic anhydride. Maleinization provides a means for inserting free acid groups in the middle of unsaturated ester chains thus increasing the functionality of the fatty acid or ester. Maleinization is carried out by heating the nonconjugated, unsaturated fatty acids and/ or esters with the anhydride at a temperature above about 200 C.

Such higher fatty acids and fatty acid esters as myristoleic acid, lauroleic acid, palmitoleic acid, oleic acid, linoleic acid, linolenic acid, eleostearic acid, arachidonic acid, dimer acids, tall oil header cut and other 10-22 carbon acids and esters thereof may be employed in preparing the adduct. The naturally occurring animal, vegetable, and marine oils such as soybean oil, linseed oil, safiiower oil, perilla oil, menhaden oil, as well as mixtures of fatty acids derived from such glyceride oils, also may be used as the source of ethylenically unsaturated material in the preparation of the adduct. Acidulated foots provide an additional inexpensive source of unsaturated fatty acid. These foots are obtained by acidulating soap stock produced as a by-product in the refining of glyceride oils with alkali. The soap stock or residue CCH2CH2 O and additionally contains polyamino radicals. The polymer is prepared from a polyepoxide and about 5-50% of caprolactam based on the weight of the oxirane-containing composition and about 150% based on the weight of the oxirane-containing composition of the polyamine. Preferred quantities of caprolactam are around 210% based on the weight of the oxirane-containing composition, while preferred quantities of the polyamine are around 1-20% based on the weight of the oxirane-containing composition.

Polyepoxides which are condensed with the caprolactam include generally those oxirane-containing compositions having more than one epoxy group per molecule and include esters of oxirane-substituted higher fatty acids, particularly dihydric and other polyhydric alcohol esters of such fatty acids and mixtures thereof. Glyceride esters of oxirane-containing higher fatty acids substantially free of terminal oxirane groups are very desirable as the source of oxirane groups. Synthetic glycerides such as epoxidized triolein, epoxidized trilinolein, and epoxidized trilinolenin and monoand diglycerides of such epoxidized fatty acids are satisfactory polyepoxides. Naturally occurring animal, vegetable, and marine triglycerides when epoxidized to contain more than one oxirane group per molecule represent a convenient and economical source of epoxidized esters. The more highly epoxidized glycerides, that is epoxidized perilla oil or epoxidized linseed oil, when substantially completely epoxidized are characterized by oxirane oxygen content of more than about 7% and may, in some cases, analyze at 9.5% oxirane oxygen and above. The high functionality of such compositions permits the production of harder copolymers of higher tensile strength in a shorter period of time than where less highly epoxidized materials are employed.

Epoxidized tallow, epoxidized cottonseed oil, epoxidized soybean oil, epoxidized menhaden oil, epoxidized sardine oil, epoxidized sperm oil, epoxidized safflower oil are a few of the many epoxidized naturally occurring glycerides which can be used in forming the copolymer. The fatty acids derived from these naturally occurring glycerides when esterified with lower aliphatic, monohydric, dihydric, trihydric, tetrahydric, and pentahydric alcohols result in compositions which are also a desirable source of the polyepoxide. Examples of such alcohols which may be esterified with epoxy fatty acids to form suitable esters include lower glycols, glycerol, erythritol, mannitol, pentaerythritol and sorbitol. Aliphatic polyhydric alcohol esters of oxirane-containing fatty acids of 10-22 carbons generally are employed in preparing copolymers having high strength.

The polyamine reactant utilized in forming the copolymer can be any primary or secondary aliphatic or aromatic amine having more than one amino group. Alkylene polyamines such as the diamines, triamines, tetraamines, pentamines, and hexamines are included in the definition of the polyaminel reactant. Specific alkylene polyamines include ethylene diamine, trirnethylene diamine, pentamethylene diamine, hexamethylene diamine,

diethylene triamine, triethylene tetramine, tetraethylene pentamine, and long-chain polyamines such as the N- alkyl alkylene polyamines wherein the alkyl substitution comprises a long-chain alkyl group of 10-22 carbons. Aromatic polyamines include o-phenylene diamine, mphenylene diamine, o-tolidine, 2,4-tolidine, 2,4-tolylene diamine, 1,4-diamino napthalene, and other aromatic polyamines free of interfering substituents.

While as has been noted previously the core oil can be made up exclusively of the polymer, it is preferred that this component of the binding agent be present in a minor amount and the maleic anhydride adduct be present in a major amount. As little as 1% of the polyepoxide-caprolactam polymer based on the weight of the binder, the remainder being the adduct, provides a highly effective core oil. As the amount of the polymer in the core oil composition is increased the strength of the core increases. A desirable core oil which can in combination with the sand be baked in a reasonably short period of time to provide a core of substantially mechanical strength is made up of 5-50% by weight of the polymer. Proportions of the polymer and prereacted maleinized unsaturated material can be adjusted by those skilled in the art to satisfy the requirements for a given casting or molding operation.

The core oil possesses a high degree of adherence for the sand particles and flows in and around the particles, forming a film enveloping the particles. Good mechanical strength in the core is provided by small amounts of the binder and for this reason the core oil is very economical. Amounts of core oil as low as 0.5% based on the weight of the mineral core material results in cores having a high degree of mechanical strength and amounts up to around 4% based on the weight of the mineral core material provide some advantages. Larger amounts while operable are uneconomical.

The following examples showing specific embodiments of the invention are intended as being illustrative rather than limitative of the invention.

Example I The copolymer reactants are mixed in a 2-liter flask. The reactants are:

Grams Epoxidized linseed oil (oxirane 9.0%) 1200 Caprolact-am 48 Triethylene tetramine 96 The reactants are mixed and the flask is evacuated with a Water aspirator while the mixture is heated in a boiling water bath for minutes. The reaction mixture is then cooled to room temperature and 72 grams of trioxymethylene is added. The trioxymethylene is not necessary if the core oil is to be used within about two weeks. The trioxymethylene is employed as a viscosity stabilizer and prevents gelling on long standing. The polymer reaction product is then warmed until the trioxymethylene is dissolved and a maleic anhydride adduct of soybean oil is added.

The adduct is prepared by heating 4883 grams of soybean oil and 781 grams maleic anhydride at 210 C. for one hour and then cooling to room temperature. The mixture of adduct and polymer is agitated until a homogeneous mixture is obtained.

The core is prepared by adding 3 grams of the mixture prepared above to grams of foundry grade dry silica sand and 30 gram portions of this mixture are placed in aluminum foil molds 2% inches in diameter. The sand and binder are tamped into the mold with a /2 pound weight and the formed core is then removed from the mold and baked at 500 F. for 20 minutes. The sand cores which are produced and which are about A inch thick cannot be broken in the hands. Similar cores prepared employing drying oils under identical conditions kwere so Weak that they could easily be broken with the ands.

Example I] The following ingredients were mixed in a 2-liter flask:

Grams Epoxidized linseed oil (oxirane content 9.0%) 1200 Caprolactam 48 m-Phenylene diamine 28.8

The contents of the flask are agitated and the flask is evacuated with a waer aspirator, while heating the contents in a boiling water bath for 60 minutes.

A maleic anhydride adduct prepared by heating 500 grams soybean oil and 80 grams maleic anhydride at 200 C. for one hour and cooled to room temperature was incorporated with 145 grams of the polymer prepared above. The components were agitated until the mixture was homogeneous and 0.6 gram of this core oil was mixed with 30 grams of sand and the core composition was molded in aluminum cups as in Example I. The core was removed from the mold and overbaked by exposing the core to a temperature of 500 F. for 3 hours. The resulting disk cannot be broken in the hands. Similar cores prepared in exactly the same fashion except that soybean oil is substituted for the core oil, produce disks so weak that they can easily be broken with the hands.

Example III A flask containing:

Grams Epoxidized linseed oil (oxirane oxygen 9.0%) 1200 Capr-olactam 48 T riethylene tetramine 19.2

was heated in a boiling water bath while agitating the reactants and evacuating the flask with a water aspirator. Heating was continued for a period of 120 minutes. The reaction product was cooled to room temperature and 14.4 grams trioxymethylene was added while vigorously agitating the mixture.

12.82 grams of the reaction product and 0.13 gram of diphenolic acid were mixed and heated at 180 F. for one hour during which the mixture was agitated. The product was then cooled to room temperature and an adduct prepared by heating 44.7 grams of soybean oil and 7.1 grams of maleic anhydride at 210 C. for one hour was added and a homogeneous mixture was formed. 0.6 gram of this homogeneous mixture was mixed with 30 grams of sand and a sand core was prepared in the aluminum dishes as in Example I. The core was overbaked by exposing to a temperature of 500 F. for 5 hours in an oven. A very strong core that cannot be broken in the hands results. A similar core prepared simultaneously under identical conditions with the exception that linseed oil is substituted as the core oil is easily broken with bare hands.

Exnmple IV A mixture of epoxidized linseed oil having an oxirane content of 9.0% (1200 grams) caprolactam (48 grams), and triethylene tetramine (19.2 grams) was formed and agitated during heating under vacuum at 100 C. for 2 hours. At the end of this time 14.4 grams trioxymethylene was added and the reaction mixture was warmed until the trioxymethylene dissolved therein.

The adduct was prepared by cooling 1600 grams of a tall oil header cut to about 7.5 C. and filtering on a vacuum filter. 100 grams of the filtrate and 5.7 grams maleic anhydride -was placed in a reaction vessel and the mixture agitated and heated at approximately 210 C. for 4 hours. 4.50 grams of this reaction product was mixed with 0.5 gram of the polymer reaction product until a homogeneous liquid was formed. 0.6 gram of this homogeneous mixture was mixed with 30 grams of silica foundry sand and a sand core disk was prepared in the usual fashion. The core was baked at 500 F. for

20 minutes. The strength of the core is comparable to those prepared in accordance with the preceding examples.

Example V Preparation of the polymer in two stages is sometimes preferred. The first stage of the reaction, which is carried out at any temperature below about 300 C. and preferably around -120 C., is believed to involve reaction between the caprolactam and the oxirane group of the epoxidized fatty material. The second stage probably involves polymerization of the caprolactam rings to form polyarnide chains. This polymerization is catalyzed by the presence of traces of moisture normally present as an adventitious constituent of the raw materials. This second stage involves heating at a temperature above about 80 C. and below about 500 C., at which point some thermal decomposition of the product may occur. The second stage of the reaction may conveniently be carried out during baking of the sand core.

A mixture of 942 grams epoxidized soybean oil (oxirane oxygen 7.0%) and 450 grams caprolactam was formed and the mixture was heated at 200 C. while agitating for a period of one hour. The temperature was then reduced to C. and 148 grams of m-phenylenediamine was added. The mixture was held at around 120 C. for 2 hours and then cooled to room temperature. A maleic anhydride adduct prepared by heating 200 grams of corn oil foots with 11.4 grams of maleic anhydride at 210 C. for 4 hours was added to 21.1 grams of the preformed polymer and the two components were mixed until uniform.

The mixture of the adduct and polymer (0.6 gram) was incorporated in 30 grams of sand and the mixture distributed throughout the sand. The core materialbinder mixture was molded in aluminum cups in the manner described previously. The core was removed from the cups and baked at 550 F. for one hour. This core possessed considerable strength, particularly when compared to a core prepared in the identical fashion utilizing ordinary linseed oil as core oil.

Example VI A mixture of:

Grams Epoxidized menhaden oil (oxirane oxygen 8.6%) 300 Caprolactam 12 Tetraethylene pentamine 96 was formed and mixed and the uniform mixture was allowed to stand at room temperature (about 20 C.) for 72 hours. The mixture was added to a maleic anhydride adduct prepared by heating 2,000 grams of menhaden oil with 86 grams maleic anhydride at C. for 6 hours. The adduct and polymer were mixed until homogeneous and 3 grams of this mixture was employed in preparing disks as in the previous examples. The core was baked at 400 F. for 50 minutes to provide a strong disk which could not be broken easily.

While all of the cores prepared in accordance with the invention exhibit a high degree of mechanical strength, the cores prepared from core oil compositions having highly epoxidized oils as a component thereof are stronger than those prepared from core oil compositions having an epoxidized oil of lower oxirane content. The core prepared from a core oil derived from epoxidized linseed oil, as in Example I, was much more diflicult to break with pliers than the core prepared from epoxidized soybean oil in Example V.

Since the compositions of the invention function as heat hardenable binders they are very versatile in areas of use other than as core oils. The compositions can be employed as binders in forming laminates of glass and in fabricating fibrous glass products.

Obviously, many variations and modifications of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof. Therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A core comprising a formed and baked mixture'of core material and core oil comprising a mixture of the reaction product of an ester of an oxirane-containing higher fatty acid caprolactam, and a polyamine with a maleic anhydride adduct of an organic compound containing nonaromatic ethylenic unsaturation selected from the group consisting of ethylenically unsaturated hydrocarbons, ethylenically unsaturated fatty acids and ethyl enically unsaturated fatty acid esters.

2. A core comprising a formed and baked mixture of core material and about 0.5-4% of the mixture comprising a mixture of the reaction product of an ester of an oxirane-containing higher fatty acid, caprolactam, and a polyamine with a maleic anhydride adduct of an ethylenically unsaturated higher fatty acid.

3. A nonoxidizing core oil composition comprising: a maleic anhydride adduct of an organic compound containing nonaromatic ethylenic unsaturation selected from the group consisting of ethylenically unsaturated hydrocarbons, ethylenically unsaturated fatty acids and ethylenically unsaturated fatty acid esters as a major ingredient and as a minor ingredient the reaction product of an ester of an oxirane-containing higher fatty acid, caprolactam, and a polyamine.

4. A core oil composition comprising: a major amount of a maleinized, unsaturated fatty acid and a minor amount of the reaction product of an ester of an oxiranecontaining higher fatty acid, caprolactam, and a polyamine.

5. A core oil composition comprising: a major amount of a maleic anhydride adduct of an organic compound containing nonaromatic ethylenic saturation selected from the group consisting of ethylenically unsaturated hydrocarbons, ethylenically unsaturated fatty acids and ethylenically unsaturated fatty acid esters and a minor amount of the reaction product of an ester of an oxiranecontaining higher fatty acid caprolactam, and an alkylene polyamine.

6. A core oil composition comprising: a major amount of a maleic anhydride adduct of an organic compound containing nonaromatic ethylenic unsaturation selected from the group consisting of ethylenically unsaturated hydrocarbons, ethylenically unsaturated fattyacids and ethylenically unsaturated fatty acid esters and a minor amount of the reaction product of an ester of an oxiranecontaining higher fatty acid caprolactam, and an aromatic polyamine.

7. A core oil composition which has a high degree of adherence for core material and which undergoes cure rapidly comprising: a homogeneous mixture of (1) the reaction product of an ester of an oxirane-containing higher fatty acid having more than one oxirane group per molecule, caprolactam, and a polyamine and (2) an adduct of a lower aliphatic unsaturated dicarboxylic acid anhydride and an organic compound containing nonaromatic ethylenic unsaturation.

8. The composition of claim 7 wherein the fatty acid ester is an aliphatic polyhydric alcohol ester.

. 9. The composition of claim 7 wherein the acid anhydride is maleic anhydride.

10. The composition of claim 7 wherein the organic compound containing ethylenic unsaturation is an unsaturated higher fatty acid.

11. The composition of claim 7 wherein the organic compound containing ethylenic unsaturation is an unsaturated hjgher fatty acid ester.

References Cited by the Examiner UNITED STATES PATENTS 2,847,342 8/1958 Kohn 26047 2,847,343 8/1958 Kohn 26047 2,940,944 6/ 1960 Christenson 26023 2,947,711 8/1960 Cooke et al. 26018 2,967,837 1/1961 Greenfield 26018 3,036,975 5/1962 Taub 260830 3,107,403 10/1963 Moore 22-194 LEON J. BERCOVITZ, Primary Examiner.

M. STERMAN, Examiner. 

1. A CORE COMPRISING A FORMED AND BAKED MIXTURE OF CORE MATERIAL AND CORE OIL COMPRISING A MIXTURE OF THE REACTION PRODUCT OF AN ESTER OF AN OXIRANE-CONTAINING HIGHER FATTY ACID CAPROLACTAM, AND A POLYAMINE WITH A MALEIC ANHYDRIDE ADDUCT OF AN ORGANIC COMPOUND CONTAINING NONAROMATIC ETHYLENIC UNSATURATION SELECTED FROM THE GROUP CONSISTING OF ETHYLENICALLY UNSATURATED HYDROCARBONS, ETHYLENICALLY UNSATURATED FATTY ACIDS AND ETHYLENICALLY UNSATURATED FATTY ACID ESTERS. 